Programming language and runtime environment that allows compiled Java programs to run unchanged on most hardware and software platforms

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74
votes
7answers
101k views

How to determine JAVA_HOME on Debian/Ubuntu?

On Ubuntu it is possible to have multiple JVMs at the same time. The default one is selected with update-alternatives. But this does not set the JAVA_HOME environment variable, due to a debian policy. ...
69
votes
9answers
178k views

Can't seem to disable Java Automatic Update

I'm just tweaking out my new Windows 7 laptop and wanted to disable the automatic Java updating (and thus kill the silly jusched.exe background process), but I can't seem to get it to actually turn it ...
50
votes
7answers
100k views

Top - what does Virtual memory size mean? …linux/ubuntu

I am running top to monitor my server performance and 2 of my java processes show virtual memory of up to 800MB-1GB. Is that a bad thing? What does virtual memory mean? And oh btw, I have swap of ...
47
votes
5answers
92k views

Practical maximum open file descriptors (ulimit -n) for a high volume system

We recently began load testing our application and noticed that it ran out of file descriptors after about 24 hours. We are running RHEL 5 on a Dell 1955: CPU: 2 x Dual Core 2.66GHz 4MB 5150 / ...
44
votes
5answers
5k views

How do I install the JRE on a Windows server without Oracle adware?

I would like to install Java on one of our servers, but I am reticent due to Oracle's bundling of an Ask.com toolbar and some virus scanner. I've read that the java updater even installs these for ...
34
votes
4answers
120k views

Where to set java heap options (e.g. -Xmx) for Tomcat 6 under Ubuntu 9.04?

I'm running Tomcat using the tomcat6 package from Ubuntu 9.04, which makes a daemon out of Tomcat using jsvc. I'd like to know the proper way to set Java heap options like -Xmx for Tomcat. I'd like to ...
27
votes
9answers
8k views

Is it a Best Industry practice to restart web servers periodically? [closed]

We have a web application (developed by a third party) that runs on Tomcat. We have been getting very bad performance from the application. The application developer is claiming that it is an ...
20
votes
7answers
97k views

What is the value of JAVA_HOME for CentOS?

I have install java through yum on CentOS, however another java programme needs to know what the JAVA_HOME environmental variable is. I know all about setting environmental variables, but what do I ...
16
votes
3answers
17k views

How do you manage Java in your Windows/Active Directory environment?

Like I suppose a lot of people, we have a Windows/Active Directory environment and a lot of internal line of business apps that require Java. Our experience is that Java does not play nice in such a ...
15
votes
5answers
8k views

I'm designing a system to handle 10000 TCP connections per second, what problems will I run into?

I have a relatively new 8-core box running CentOS. I would like to develop a stats server that uses TCP. It's very simple, it accepts a TCP connection, increments a counter and closes the connection. ...
13
votes
2answers
24k views

Adding lines to /etc/profile with puppet?

I use puppet to install a current JDK and tomcat. package { [ "openjdk-6-jdk", "openjdk-6-doc", "openjdk-6-jre", "tomcat6", "tomcat6-admin", "tomcat6-common", "tomcat6-docs", ...
13
votes
4answers
421 views

How to convince my Administrator that Java ON A SERVER is not insecure per se?

The Application We have a small Java application which uses some Camel routes to pick up uploaded files from a webserver, process them and send out some e-mails with the results. The server on which ...
12
votes
2answers
20k views

How can I upgrade to Java 1.8 on an Amazon Linux Server?

I tried sudo yum update but it just keeps java "1.7.0_75". I need 1.8 for it to work with another application but can't figure out how to upgrade it. Do I need to manually install it somehow? There's ...
12
votes
6answers
9k views

What consumes memory in java process?

we are trying to investigate memory usage of java process under moderate load. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 12663 test 20 0 8378m 6.0g 4492 S 43 8.4 ...
12
votes
2answers
38k views

what is .crt and .key and how can I generate them?

SSLEngine on SSLCertificateFile /etc/httpd/conf/login.domain.com.crt SSLCertificateKeyFile /etc/httpd/conf/login.domain.com.key SSLCipherSuite ALL:-ADH:+HIGH:+MEDIUM:-LOW:-SSLv2:-EXP
12
votes
4answers
38k views

Cannot switch, ssh to specific user: su: cannot set user id: Resource temporarily unavailable?

/var/log/secure: su: pam_keyinit(su-l:session): Unable to change UID to 500 temporarily su: pam_keyinit(su-l:session): Unable to change UID to 500 temporarily su: pam_unix(su-l:session): session ...
12
votes
2answers
10k views

Disabling SSLv3 but still supporting SSLv2Hello in Apache

Many SSL clients, notably JDK 6, use the SSLv2Hello protocol to handshake with the server. Using this protocol does not mean you are using SSL 2.0 or 3.0 for that matter; it is merely a handshake to ...
11
votes
8answers
40k views

Batch file to uninstall all Sun Java versions?

I'm setting up a system to keep Java in our office up to date. Everyone has all different versions of Java, many of them old and insecure, and some dating back as far as 1.4. I have a System Center ...
11
votes
6answers
12k views

Open source tomcat log viewer

I'm managing several tomcat instances (aprox 30-35) and looking for some console to centralize the logs. I tried php-syslog-ng before (no with tomcat), and found it useful. I would like that these ...
10
votes
4answers
3k views

ps aux hanging on high cpu/IO with java processes

I'm having some issues with java process and nrpe checks. We have some processes that sometimes use 1000% cpu on a 32 core system. The system is pretty responsive until you do a ps aux or try to ...
10
votes
1answer
16k views

How can I restrict the java plugin to run only on certain sites in Internet Explorer?

I want to secure our centrally managed computers better and it is very difficult to automatically deploy the java runtime, but how to do that is another question. I find the security of Java ...
9
votes
2answers
2k views

How do you get the latest update for Java 6?

An application my company is considering buying requires Java 6. I am concerned that this is quite out of date and am recommending against the application as a result. But it seems that Oracle do ...
9
votes
6answers
14k views

How to block access to a file from being served by Tomcat?

We have a few tomcat servers and we just discovered that some files that we don't want public to have access to those files. To exemplify: Let say we have a folder /var/www/html/ that we are ...
9
votes
5answers
1k views

How do I find the cause for a huge difference in performance between two identical Ubuntu servers?

I am running two Dell R410 servers in the same rack of a data center (behind a load balancer). Both have the same hardware configuration, run Ubuntu 10.4, have the same packages installed and run the ...
9
votes
4answers
2k views

JVM Memory Consumption

I am trying to run tomcat on a low memory system (150-256Mb). Even though I start the JVM with -Xmx64m (which should be the default anyway), the process immediately takes up 200Mb+. I wonder why the ...
8
votes
4answers
4k views

is it possible to install java without the browser plugin?

I need java, but I don't want any browser to be able to access it. Is it possible to remove the whole applet/browser plugin code?
8
votes
1answer
387 views

Good practices regarding discontinued software in production (OpenDS)?

How bad is it to use OpenDS, which is not actively maintained, and had the last patch in 2010, and require JDK6(which is also obsolete) in a production environment?(Although at the backend and not ...
8
votes
5answers
6k views

Suggestions for free/cheap asset/patch management software (Adobe, Java, etc)

I am using WSUS for Microsoft patching but would like something that will inventory and patch Adobe, Java, Firefox, Quicktime, etc. I have used Lumension in the past and it was OK but it is too ...
8
votes
3answers
42k views

How to get a linux network log?

We have a java server running in linux at a specific port that accepts persistent connections for thousands and thousands of users. Recently our clients are not able to connect with a time out error. ...
8
votes
3answers
6k views

How can I install a headless JDK on an Ubuntu Jaunty server?

I recently set up a build server that requires a JDK to run (for example, to compile the Java sources). The OpenJDK package in Ubuntu pulls in the OpenJDK JRE as a dependency which, in turn, depends ...
8
votes
1answer
62k views

Differences between classes12.jar, ojdbc14.jar, ojdbc5.jar and ojdbc6.jar

We are planning to upgrade our application servers to a new version of JRun which is carrying with it an upgrade from Java 1.4 to Java 1.6. As part of that, we have been testing various pieces of our ...
8
votes
1answer
2k views

Tomcat: possible to exclude jars during app deployment?

By default, Tomcat prevents webapps from loading several .jars which are part of the Tomcat distribution (eg the servlet and JSP APIs) - is it possible to configure others to also be excluded? If it ...
8
votes
1answer
11k views

How can I block Java updates, network-wide?

Java is constantly prompting users to upgrade and, when they do, it tries to install all sorts of other things which we must uninstall. Lately it installs a backup program called Carbonite. We’ve ...
8
votes
1answer
102 views

How do I build a Linux environment that specifies specific versions of packages?

I am creating a dockerfile that runs a custom application that is tied to a specific version of Java. I'm using a centos7 base image because that's what an article I was referring to was using and ...
7
votes
7answers
29k views

Run Jar in Background on Linux

I have a jar that runs forever (infinite loop with socket listening thread) and need it to run in the background at all times. An example would be: "java -jar test.jar" How do I do this? Thanks in ...
7
votes
4answers
15k views

How can I install WildFly 8.0.0.Final as service on Ubuntu Linux?

I am trying to install the WildFly 8.0.0.Final application server on a Virtual Machine running Ubuntu 12.04 LTS. I've done some searches on Google, but I found only third-party scripts and, I think, ...
7
votes
2answers
10k views

SSL Certificate Error: certificate_unknown

I want to create push notification server and while installing SSL certificate and .p12 file in server we are facing the below error: I want to know what is the wrong with ssl certificate because I am ...
7
votes
4answers
9k views

Constantly Increasing swap size in Linux and Swap space not being reclaimed?

I have a 8GB RAM linux box on which 4 tomcat servers are running. One of the them is set to 3000MB memory(jvm -Xms and -Xmx setting) and others are set to 1500MB. The swap partition is also set to ...
7
votes
5answers
15k views

Tomcat 6.0 service does not start: java/lang/NoClassDefFoundError

I installed Tomcat on my Windows server but I can't get it to start. I start the service and I see the progress bar, but it fails. I installed the Java Runtime Environment Version 6 and created ...
7
votes
1answer
10k views

Copy a Java keystore on one machine to another?

I have a keystore on one machine (at /root/.keystore) and I want to move it to another machine at the same location. Currently, the second machine doesn't have a keystore at /root/.keystore, is there ...
7
votes
3answers
6k views

Sending email using SMTP (Gmail) from Hudson CI

How can I set up Hudson CI so that I can send out emails from the server following a build failure? At the moment all I get is the following error: com.sun.mail.smtp.SMTPSendFailedException: 530 ...
7
votes
1answer
4k views

Tomcat Excessive Memory Consumption

I have a fresh server running Ubuntu 11.04 (Natty) (64-bit). I started off by installing openjdk and tomcat6. When the Tomcat server starts up, it immediately uses 480+ MB of memory. This seems way ...
6
votes
5answers
31k views

How to change default /tmp to /home/user/tmp

Is there an environment variable to set the temporary directory on debian based systems? I have a java applet that uses that environement variable and it's getting confused when launching two ...
6
votes
4answers
218 views

Crashing my disk using Java

I have a Java program that must do the following 3 things: Download a file from a website. Run the file trough testA and testB (both in java) Delete the file and save the test results on the disk. ...
6
votes
5answers
10k views

How to reliably take Java Heap Dumps?

My team is running into difficulties when trying to take good heap dumps triggered by OutOfMemoryErrors. For specific reasons we are currently taking the dumps with jmap called from a bash script ...
6
votes
5answers
3k views

OpenJDK vs. Sun Java6 on Ubuntu

Due to past (bad) experience resulting from the GCJ stuff being provided by default on certain distributions, I've always traditionally installed the official Sun Java package on servers. On Ubuntu ...
6
votes
5answers
29k views

Java Deployment Rule Set via AD Enterprise CA

My goal is to get a Java Deployment Rule Set in place in my organization, but I do not want to pay third-party certificate authority for a code signing cert when we have a working CA running through ...
6
votes
1answer
14k views

How to switch between TLS 1.0 and SSL 3.0 at Java/JRE level?

I am using java 1.6. I have setup my tomcat as my ssl enabled server. And i have setup a ssl enabled client (java code). When i do a communication from my client to server. In java ssl dump in tomcat ...
6
votes
1answer
1k views

Is it appropriate to use HeapDumpOnOutOfMemoryError in Production?

We have been struggling to diagnose the cause of an OutOfMemoryError we experienced on one of our production servers. Our attempts to reproduce the issue in soak tests have so far failed, and we are ...
6
votes
2answers
16k views

Which Java version should I run Jenkins with?

Reference: Jenkins Users :: Jenkins on Windows: Java + JRE (version) confusion Which Java version should I run Jenkins with (on Windows)? Should I use the included JRE of the Windows master? Should ...